Fibrous protein fragments similar to those in the brains of people with Alzheimer’s disease can pull carbon dioxide out of the air.

Existing methods to capture CO2 have drawbacks. Some require toxic materials and large amounts of energy; others falter when exposed to water vapor, which fossil fuel combustion releases alongside CO2.

Because building blocks of proteins bind CO2 in blood, scientists including David Eisenberg of UCLA exposed protein fibers called amyloids to CO2 in air, mimicking c...